1. Field of the Invention
The present invention relates to a magnetic head, a head assembly, and a magnetic recording/reproducing apparatus.
2. Description of the Related Art
In order to improve writing performance of information, various improvements have been made in a perpendicular recording magnetic head to be used for a magnetic recording/reproducing apparatus such as a hard disk drive (HDD). In particular, research and development have been vigorously conducted regarding the problem of accidentally erasing information recorded on a magnetic disk being a recording medium.
For example, Japanese Unexamined Patent Application Publication No. 2006-164463 discloses a technology in which a return path layer for absorbing a return magnetic flux from a magnetic disk is shaped to have a width increasing toward a floating surface, thereby reducing the magnetic field strength at its ends in a track width direction.
Moreover, Japanese Unexamined Patent Application Publication No. 2008-276902 discloses a technology in which an auxiliary yoke layer laid on a main magnetic pole layer is provided with a distinctive flared part, thereby preventing the occurrence of pole lock-up.
Furthermore, Japanese Unexamined Patent Application Publication No. 2008-276819 discloses a technology in which an auxiliary yoke layer for circulating a magnetic flux from a return path layer to a main magnetic pole layer is formed across a plurality of layers in the manner of multi-stage connection, thereby stabilizing magnetization components of individual layers in a track width direction based on shape anisotropy.
Meanwhile, the present inventors tried to improve writing performance, based on their unique viewpoint, by uniformly narrowing the track-wise widths of a main magnetic pole layer and an auxiliary yoke layer laid thereon. As a result, it has been found that characteristics such as recording magnetic field strength, bit error rate (BER), and S/N can be improved, particularly, in a low-amperage range and a high-frequency range of a write current to be supplied to a coil. That is, the above improvement results in improving magnetic saturation characteristics of a magnetic head with respect to the write current.
However, on the other hand, it has also been found that the strength of a recording magnetic field to be applied to tracks adjacent to a target track for writing can be increased as compared with the one having a conventional width, increasing the risk of wide area track erase (WATE).